Ocean heat transport and water vapor greenhouse in a warm equable climate: a new look at the low gradient paradox

The authors study the role of ocean heat transport (OHT) in the maintenance of a warm, equable, ice-free climate. An ensemble of idealized aquaplanet GCM calculations is used to assess the equilibrium sensitivity of global mean surface temperature and its equator-to-pole gradient (ΔT) to variations in OHT, prescribed through a simple analytical formula representing export out of the tropics and poleward convergence. Low-latitude OHT warms the mid- to high latitudes without cooling the tropics; increases by 1°C and ΔT decreases by 2.6°C for every 0.5-PW increase in OHT across 30° latitude. This warming is relatively insensitive to the detailed meridional structure of OHT. It occurs in spite of near-perfect atmospheric compensation of large imposed variations in OHT: the total poleward heat transport is nearly fixed. The warming results from a convective adjustment of the extratropical troposphere. Increased OHT drives a shift from large-scale to convective precipitation in the midlatitude storm tracks. Warming arises primarily from enhanced greenhouse trapping associated with convective moistening of the upper troposphere. Warming extends to the poles by atmospheric processes even in the absence of high-latitude OHT. A new conceptual model for equable climates is proposed, in which OHT plays a key role by driving enhanced deep convection in the midlatitude storm tracks. In this view, the climatic impact of OHT depends on its effects on the greenhouse properties of the atmosphere, rather than its ability to increase the total poleward energy transport.

The Kurdish conflict: international humanitarian law and post-conflict mechanisms

This book is highly topical considering the recent resurgence of violence by the PKK, the incursions into Northern Iraq by the Turkish army and security forces and Turkey’s EU accession negotiations. Turkey has become an increasingly important player in Middle Eastern geopolitics. More than two decades of serious conflict in Turkey are proving to be a barrier to improved relations between Turkey and the EU. This book is the first study to address fully the legal and political dimensions of the conflict, and their impact on mechanisms for conflict resolution in the region, offering a scholarly exploration of a debate that is often politically and emotionally highly charged. Kerim Yildiz and Susan Breau look at the practical application of the law of armed conflicts to the ongoing situation in Turkey and Northern Iraq. The application of the law in this region also means addressing larger questions in international law, global politics and conflict resolution. Examples include belligerency in international law, whether the ‘war on terror’ has resulted in changes to the law of armed conflict and terrorism and conflict resolution. The Kurdish Conflict explores the practical possibilities of conflict resolution in the region, examining the political dynamics of the region, and suggesting where lessons can be drawn from other peace processes, such as in Northern Ireland. This book will be of great value to policy-makers, regional experts, and others interested in international humanitarian law and conflict resolution.

Quantifying the roles of ocean circulation and biogeochemistry in governing ocean carbon-13 and atmospheric carbon dioxide at the last glacial maximum

We use a state-of-the-art ocean general circulation and biogeochemistry model to examine the impact of changes in ocean circulation and biogeochemistry in governing the change in ocean carbon-13 and atmospheric CO2 at the last glacial maximum (LGM). We examine 5 different realisations of the ocean's overturning circulation produced by a fully coupled atmosphere-ocean model under LGM forcing and suggested changes in the atmospheric deposition of iron and phytoplankton physiology at the LGM. Measured changes in carbon-13 and carbon-14, as well as a qualitative reconstruction of the change in ocean carbon export are used to evaluate the results. Overall, we find that while a reduction in ocean ventilation at the LGM is necessary to reproduce carbon-13 and carbon-14 observations, this circulation results in a low net sink for atmospheric CO2. In contrast, while biogeochemical processes contribute little to carbon isotopes, we propose that most of the change in atmospheric CO2 was due to such factors. However, the lesser role for circulation means that when all plausible factors are accounted for, most of the necessary CO2 change remains to be explained. This presents a serious challenge to our understanding of the mechanisms behind changes in the global carbon cycle during the geologic past.

Estimating the direct aerosol radiative perturbation: impact of ocean surface representation and aerosol non-sphericity

Atmospheric aerosols are now actively studied, in particular because of their radiative and climate impacts. Estimations of the direct aerosol radiative perturbation, caused by extinction of incident solar radiation, usually rely on radiative transfer codes and involve simplifying hypotheses. This paper addresses two approximations which are widely used for the sake of simplicity and limiting the computational cost of the calculations. Firstly, it is shown that using a Lambertian albedo instead of the more rigorous bidirectional reflectance distribution function (BRDF) to model the ocean surface radiative properties leads to large relative errors in the instantaneous aerosol radiative perturbation. When averaging over the day, these errors cancel out to acceptable levels of less than 3% (except in the northern hemisphere winter). The other scope of this study is to address aerosol non-sphericity effects. Comparing an experimental phase function with an equivalent Mie-calculated phase function, we found acceptable relative errors if the aerosol radiative perturbation calculated for a given optical thickness is daily averaged. However, retrieval of the optical thickness of non-spherical aerosols assuming spherical particles can lead to significant errors. This is due to significant differences between the spherical and non-spherical phase functions. Discrepancies in aerosol radiative perturbation between the spherical and non-spherical cases are sometimes reduced and sometimes enhanced if the aerosol optical thickness for the spherical case is adjusted to fit the simulated radiance of the non-spherical case.

Construction contracts: law and management. 4th edition

This is a fully revised edition of the UK’s leading textbook on the law governing construction contracts and the management and administration of those contracts. Although the legal principles involved are an aspect of general contract law, the practical and commercial complexities of the construction industry have increasingly made this a specialist area. This new edition has been brought up to date with recent cases and developments in the law as it stands at March 2007. The basic approach of the book has been retained. Rather than provide a commentary on standard-form contracts, our approach is to introduce the general principles that underlie contracts in construction, illustrating them by reference to the most important standard forms currently in use. Some of the common standard-form contracts have been revised since the previous edition, and the text has been revised to take account of these changes. Practitioners (consultants, builders, clients and lawyers) will find this an extremely useful source of reference, providing in-depth explanations for all of the features found in contemporary construction contracts, with reasons. A unique feature of this book is the way that it brings together the relevant principles of law with the practical issues arising in construction cases. It is a key text for construction undergraduates and postgraduates as well as for those taking the RIBA Part III and CIOB Part II examinations.

It's all about climate change, stupid! Exploring the relationship between environmental law and climate law

This comment analyses the relationship between climate law and environmental law. It examines this relationship from both a normative and a descriptive point of view. Normatively, it brings together various strands from some of the existing literature to form an overall model of the relationship—looking at ‘crowding out’, ‘crowding in’, ‘climate exceptionalism’ and adding in ‘climate unexceptionalism’. In descriptive terms, it considers, inter alia, ‘super wickedness’, instruments and governance, mitigation and adaptation.